Monday, February 20, 2017

CQ skimmer server during ARRL CW 2017 at OL7M

   A week ago I ordered nice piece of HW not only as measurement tool: Red Pitaya
This is really nice piece of HW with nice web tools like: logic analyzer, oscilloscope, signal generator, spectrum analyser etc + SDR TRX or RX ! What more, SDR RX allows you to run up to 6  x 192kHz independant RX and it all as CW + RTTY skimmer!

   So I connected it to NA1 beverage at OL7M via the BIG RX box with BPF and preamp and there are the results :)

First hour of the ARRL CW 2017

80m and all bands in 05 UTC

 And compare the signals

RX vs TX antennas ISOLATION - OL7M 160m + 80m

   I was very interested in how big or low isolation is between beverages and TX antennas. This is quite important for RXing on the second TRX when the RUN one is TXing.

   There is a picture with all RX antennas at OL7M in 2016 - 2017:

   And the table of results:

   As you can see, beverage antenna is vertically polarized and isolation between dipole is higher. And you can imagine how strong signal is on RX input :-)

Tuesday, February 14, 2017


   After our last year participation in the  M/S category, where we set new EU record as OL7M, I have decided to run SOSB 80m. It was third time on 80m in single and my goal was new OK record. Existing great 4th place on world holds Dan OK1DIG as OL6X - 2,34 mil points. In my last two participations the gol was 1000 QSO. Unfortunately there were not good condx and lower participation too.

   A few weeks ago I had a call from Jan OK1NP and he told me about his plan to run 80m too. I agreed to be on online score ( I do have inconsistent view on it. We have got a few negative experiences with that as OL7M... Maybe there is a room for some unfair game by the over-motivated guys :) On the other hand this contest has got good SO category rules - only assisted one! I think that it should be in all the rest CQ WW contests. This could stop maybe 90 percent of all frauds.

   But back to the contest. I focused mainly on the highest score of WPX mults. It was also nice to see another guys on the online score as Filippo (IZ1LBG) IQ1RY and Milos S53X. The first hour went well and I did have 94 QSO in log although there were 4 minutes without QSO. Conditions to NA were realy great and first night brought also some NA DXs as : WK7S from AZ, Jack WA7LNW from UT. And nice DXs as Hal ZS6WB and Luis XE2B. The second night looked little bit worse but thanks to NA gray line I could work Victor V31VP, PJ6TBob C6AKQ, Preston N6SS from AZ and Robert N7WY from WY. Difficul situation is with JA. Thanks to JA band plan... I could copy 3 JAs in 3520 kHz segment but they did not run the split. I stayed above 3600 and worked 3 JAs, but there were one mistake thanks it. The most of RBN skimmers do not work above 3600!? And than my surprise, I could copy some JAs around 3570kHz, is there new RTTY segment in JA? 

   Last part brought some nice east DXs as well: BY3CN, Aravind VU2ABS,  YE1K, Francisco YV5LAY, Caros BH4TXN. From JA I worked: Taka JH4UTP, Kishi JA1OVD, Toshi JA0RUG and An JM1NKT, thanks!

   What was amazing? The score. I still can not understand in this big improvement. I used the same TX antennas as last years. The main new part of setup was second TRX with independant RX antennas. Thanks to new BIG RX ants switch box I could select inependant antennas for both TRX. What more, in some cases, I could lsn on S&P TRX during my own TX. This was perfect! I could called CQ and search for another station on the second TRX. Also when the S&P station answered to my call with last TU, I could call CQ and save some time :) Thanks this contest I do have a lot of new ideas to INBAND antennas.

   This second TRX made 226 QSOs in S&P mode. Thanks thet great conditions I worked more DXCC than in CQ WW RTTY - 71 vs 70! also number of NA stations on RTTY is nice -  226

   The result is incredible not only for me. It is 1 milion over EE8W from 2011. So what next? Maybe 40m with new yagies :)

   Finaly I would like to thanks all for QSO and to IQ1RY, S53X and OK1NP for nice fight on the online score.  


RUN TRX: IC-7800
S&P TRX: IC-7600
SO2R switching by

Antenna 1: 4SQ of sloping dipoles
Antenna 2: dipole

RX antennas:

1) 2 x 290m , QTF 320 deg to  USA
2) 205m, QTF 305 deg USA
3) 180m, QTF 90 deg  to UA9
4) 170m, QTF 45 deg to  JA
5) 235m, QTF 0 deg
6) 200m, QTF 180 deg to South
7) 220m, QTF  245 deg to SA
8) 280m, QTF 270 deg
9) K9AY single loop
10) inband beverage to 325 deg
11) beverage to 145 deg to A6

All switched to 2 independant RX with BPF and preamp, controlled over LAN.